Nassau County Executive Edward Mangano said Thursday that he expects Police Commissioner Thomas Dale to investigate and dole out "appropriate" departmental discipline after an ongoing internal probe of an off-duty cop's shooting of an unarmed cabdriver.

Suffolk County prosecutors said Thursday they have "renewed" their efforts to gain cooperation from the cabdriver in their own criminal investigation.

"We could not proceed further criminally because Mr. [Thomas] Moroughan and his girlfriend refused to cooperate with the district attorney's office . . . despite repeated requests," said Robert Clifford, spokesman for the district attorney's office. "We hope this overture is successful and results in their full cooperation with our office."

Mangano's remarks Thursday were his first public statements on a Nassau Police Internal Affairs Unit report that was the subject of a Newsday story Sunday. That police report found Nassau police Officer Anthony DiLeonardo escalated a roadside verbal dispute in Huntington on Feb. 27, 2011, when he shot at cabdriver Moroughan five times with a .38 Smith & Wesson, striking him in the chest and left arm, as his girlfriend sat beside him.

"We expect . . . [Commissioner Dale] to do a full and thorough investigation and apply the appropriate discipline as he deems fit," Mangano said. "The police commissioner has assured me he is doing his job with diligence and expeditiously."

The report recommended 19 departmental charges for what it found to be 11 unlawful acts and eight departmental rules violations by DiLeonardo. He has not been criminally charged and remains a Nassau police officer.

The report also recommended five departmental charges be brought against DiLeonardo's companion that night, Nassau police Officer Edward Bienz. He also remains on the job.

The Suffolk district attorney's office eventually dismissed charges against Moroughan and referred the matter to the Nassau Police Internal Affairs Unit.